Civil and Building Engineering.

Soils and rocks exhibit deformability in two modes that may occur independently or in combination. The two modes are deformation in shear at constant volume and deformation in volume change in either compression or dilation.

Usually, the foundation engineer considers deformation by shearing at constant volume as a short-term behavior that occurs simultaneously with the application of loading to the foundation. Conversely, the foundation engineer may consider deformation by volume change to be a long-term behavior associated with the consolidation of the soil. Both of these modes of deformation will be discussed in the appropriate chapters of this book.